Organic-based optoelectronic components, for example organic light-emitting diodes (OLEDs), are being used increasingly widely in general lighting, for example as a flat light source. An organic optoelectronic component, for example an OLED, may include an anode and a cathode with an organic functional layer system between them. The organic functional layer system may include one or more emitter layers, in which light is generated, one or more charge carrier pair generation layers (“charge generating layer”, CGL), and one or more electron barrier layers, also referred to as hole transport layers (HTL), and one or more hole barrier layers, also referred to as electron transport layers (ETL), in order to direct the flow of current.
The electrodes, for example the anode and/or the cathode, may for example include as electrically conductive elements silver nanowires, which may for example consist of elemental silver which has been grown in wire form. Typical nanowires are in this case a few tens of nm thick and several tens of μm long. In order to form the corresponding electrodes, these are distributed over a surface so that a network of silver nanowires, which is suitable for surface powering of OLEDs, is formed
One problem which may arise with electrodes having silver nanowires is that, because of the work function in the case of silver, injection of holes into the hole transport layer of the OLED may take place inefficiently. The problem can be solved by heavy doping of the hole transport layers adjacent to the silver nanowires. In this case, the doping may be greater than would be necessary in principle for pure surface conduction. Yet since the dopants and/or the doping per se are relatively expensive, instead of doping the entire HTL an additional hole injection layer (HIL) may be inserted at the silver nanowire/hole transport layer interface in order to save on dopant. This, however, may increase the process complexity in contrast to the single-layer approach in which the HIL and HTL are present in combination. As an alternative or in addition, hole-injecting polymers, for example PEDOT:PSS, may be added to the silver nanowire solution. However, the added polymers may not be compatible with every HTL material and/or may reduce the lifetime of the OLED.
Another problem may involve the processability of the material. For example, silver nanowires are inclined to agglomerate, for example form clumps. The clumped silver nanowires can no longer straightforwardly be applied uniformly on the corresponding surface. This problem may, for example, be solved by adding stabilizers to a silver nanowire solution with the dissolved silver nanowires. For example, a conductive polymer, for example PEDOT:PSS, may be added to the silver nanowire solution, although this may lead to the new problems already explained above.